Civil Engineering Association

The objective of this document is to provide constructive comments to the Post-Tensioning Institute's (PTI's) Slab-on-Ground Committee and to inform geotechnical and foundation design engineers of the Foundation Performance Association's (FPA's) concerns regarding the Post-Tensioning Institute’s “Design of Post-Tensioned Slabs-on-Ground”, (PTI Design Procedure) 3rd Edition [13].
The PTI Design Procedure is used to design a slab-on grade foundation that will respond elastically to forces the foundation is exposed to including those that are the consequence of soil pressure and soil deformation. This procedure is based on empirical data, computer generated curve fits, the geotechnical engineer’s computation of ym and em values and other variables based on site-specific geotechnical parameters. Therefore, the geotechnical and foundation design engineers should be made aware of assumptions and limitations associated with the use of this procedure.
This paper is intended to encourage refinement of the procedure by indicating areas where additional research, clarification, and / or corrections may result in better geotechnical and structural designs. This paper addresses the PTI Design Procedure, 3rd Edition. The Foundation Performance Association’s document FPA-SC-05 addresses the PTI Design Procedure, 2nd Edition [12]. The FPA refers to both editions in this paper and describes the version under discussion as the PTI Design Procedure, 2nd Edition or PTI Design Procedure, 3rd Edition. The FPA's recommendations to the PTI Committee are included in italics at the conclusion of each section.